"""
Package / supply-chain inventory snapshot.

Loads the latest committed, read-only package supply-chain inventory. The
inventory never installs dependencies, upgrades packages, writes lockfiles,
queries external CVE services, rebuilds images, or changes production routing.
"""

from __future__ import annotations

import json
from pathlib import Path
from typing import Any

from src.services.snapshot_paths import default_evaluations_dir

_DEFAULT_EVALUATIONS_DIR = default_evaluations_dir(Path(__file__))
_SNAPSHOT_PATTERN = "package_supply_chain_inventory_*.json"
_SCHEMA_VERSION = "package_supply_chain_inventory_v1"


def load_latest_package_supply_chain_inventory(
    evaluations_dir: Path | None = None,
) -> dict[str, Any]:
    """Load the newest committed package supply-chain inventory snapshot."""
    directory = evaluations_dir or _DEFAULT_EVALUATIONS_DIR
    candidates = sorted(directory.glob(_SNAPSHOT_PATTERN))
    if not candidates:
        raise FileNotFoundError(f"no package supply-chain inventory snapshots found in {directory}")

    latest = candidates[-1]
    with latest.open(encoding="utf-8") as handle:
        payload = json.load(handle)

    if not isinstance(payload, dict):
        raise ValueError(f"{latest}: expected JSON object")
    _require_schema(payload, _SCHEMA_VERSION, str(latest))
    _require_read_only_boundaries(payload, str(latest))
    _require_operation_boundaries(payload, str(latest))
    _require_rollup_consistency(payload, str(latest))
    return payload


def _require_schema(payload: dict[str, Any], expected: str, label: str) -> None:
    actual = payload.get("schema_version")
    if actual != expected:
        raise ValueError(f"{label}: expected schema_version={expected}, got {actual!r}")


def _require_read_only_boundaries(payload: dict[str, Any], label: str) -> None:
    program_status = payload.get("program_status") or {}
    if program_status.get("read_only_mode") is not True:
        raise ValueError(f"{label}: program_status.read_only_mode must be true")

    boundaries = payload.get("approval_boundaries") or {}
    blocked_flags = {
        "sdk_installation_allowed",
        "paid_api_call_allowed",
        "shadow_or_canary_allowed",
        "production_routing_allowed",
        "destructive_operation_allowed",
    }
    allowed = sorted(flag for flag in blocked_flags if boundaries.get(flag) is not False)
    if allowed:
        raise ValueError(f"{label}: approval boundaries must remain false: {allowed}")


def _require_operation_boundaries(payload: dict[str, Any], label: str) -> None:
    boundaries = payload.get("operation_boundaries") or {}
    if boundaries.get("read_only_api_allowed") is not True:
        raise ValueError(f"{label}: read_only_api_allowed must be true")

    blocked_flags = {
        "dependency_installation_allowed",
        "package_upgrade_allowed",
        "lockfile_write_allowed",
        "external_cve_lookup_allowed",
        "image_rebuild_allowed",
        "production_routing_allowed",
    }
    allowed = sorted(flag for flag in blocked_flags if boundaries.get(flag) is not False)
    if allowed:
        raise ValueError(f"{label}: operation boundaries must remain false: {allowed}")


def _require_rollup_consistency(payload: dict[str, Any], label: str) -> None:
    surfaces = payload.get("surfaces") or []
    rollups = payload.get("rollups") or {}
    total = rollups.get("total_surfaces")
    if total != len(surfaces):
        raise ValueError(f"{label}: rollups.total_surfaces must equal surfaces length")

    action_required = set(rollups.get("action_required_surface_ids") or [])
    actual_action_required = {
        surface.get("surface_id") for surface in surfaces if surface.get("status") == "action_required"
    }
    if action_required != actual_action_required:
        raise ValueError(f"{label}: rollups.action_required_surface_ids must match action_required surfaces")

    planned_next = set(rollups.get("planned_next_surface_ids") or [])
    actual_planned_next = {
        surface.get("surface_id") for surface in surfaces if surface.get("status") == "planned_next"
    }
    if planned_next != actual_planned_next:
        raise ValueError(f"{label}: rollups.planned_next_surface_ids must match planned_next surfaces")
